[boost] Missing include for boost::format

Hi, The Format headers in the main CVS are missing some #include for I/O streams. For example, if you try to compile this snippet: #include <boost/format.hpp> #include <string> int main() { std::string a = (boost::format("%1%") % 0).str(); } GCC will complain that error: base class `std::basic_ostream<char, std::char_traits<char> >' has incomplete type Regards, Guillaume